The present invention relates to a device for evaporating volatile substances, in particular insecticides and/or aromatics.
Insecticide and aromatic evaporation devices are generally known. For example, evaporation devices are known where a small plate introduced into an evaporation device and impregnated with an active ingredient is heated in order to evaporate the active ingredient. Furthermore a method is also known by which a container containing a volatile substance is introduced into a housing of an evaporation device. This container comprises a wick that conveys the substance to be evaporated by means of capillary action out of the container, whereby the wick end protruding from the container is located next to a heating element such as a ceramic block The substance is evaporated through the heat radiated by the ceramic block and can escape from the housing into the environment through aeration slits in the housing.
A disadvantage with the prior evaporation devices is that it is not possible to adapt the degree of evaporation to the prevailing room conditions or to the different sensitivities of persons present in the room. Thus, for example, in smaller rooms with insufficient air ventilation, it is desirable to lower the degree of evaporation, and this is not possible with prior evaporation devices. Furthermore adjustability of evaporation is especially desirable for insecticides, so that the degree of evaporation can be adjusted in accordance with the sensitivity of persons present in the room. This has also not been possible with the prior devices.
In order to be able to adjust the degree of evaporation to the appliwire requirements it is known to control the degree of evaporation by adjusting the heating output. Evaporation devices of that type are relatively expensive to manufacture, and are prone to malfunctions.
It is known in prior evaporation devices that the relative distance between the heating element and wick can be changed to adjust the degree of evaporation while the heating output is maintained constant (EP 0 943 344 A1). The evaporation device includes a resistance heating element with a connecting plug that is threaded into a housing element in which a container of the substances to be evaporated is located. Pin openings are provided on the housing element into which locking pins are inserted in such manner that they mesh with the threads of the plug. The distance between the resistance-heating element and a wick end protruding from the container can be changed by twisting the plug element. The plug element can be mounted eccentrically in the housing element, so that it too can be used to change the relative distance between the wick end and the resistance heating element to achieve the desired degree of evaporation. However, this method of adjusting the degree of evaporation is relatively complicated in construction and expensive to manufacture.
Another type of evaporation device in which the heating output remains constant and the relative distance between the wick and the heating element can be adjusted is known from WO 98/19526. The evaporation device comprises a housing into which a container with a wick can be screwed. The container is connected via a bushing to a swivel arm that moves in a guide slot, extending radially at an angle to the horizontal in the housing wall. Through the coupling of the swivel arm to the container the container is lifted relative to the housing in the axial direction when the swivel arm is turned radially. The wick end protruding form the container may be shifted relative to the fixed heating element. On the whole, this is a relatively expensive and complicated construction with a great number of additional components, so that the evaporating device is also expensive to manufacture.
It is therefore an object of the invention to provide an evaporation device for volatile substances, in particular insecticides and/or aromatics, which is simple in structure and can be produced economically yet the degree of evaporation can be easily adjusted to meet current requirements.
The above object is accomplished according to the present invention by providing a heating element carried on a movable heater assembly mounted in the housing. The heating element may be displaced longitudinally relative to the wick axis and can be fixed in different longitudinal positions relative to the wick end for the adjustment of the degree of evaporation. The heating element is advantageously designed as having simultaneously a double function by serving as a heating element and as a movable heater assembly so that the degree of evaporation can easily be adjusted by displacing the assembly in the longitudinal direction along the wick axis. In addition, this integration of functions makes it possible to achieve an overall space-saving and compact structure without significant expenditure for components and material. The already present components are used to adjust the degree of evaporation. An evaporation device of this type is especially well suited for small installation situations. The degree of evaporation can be adapted individually and easily to the appliwire requirements, and in addition the operation is simple and functioning is reliable.
In principle, several possibilities exist for mounting the heating element on the movable heater assembly capable of longitudinal displacement in the direction of the wick axis. In a preferred embodiment the heating element can be fixed on the housing by means of a clamp connection and/or a locking connection snapped. In another preferred embodiment, the movable heater assembly is fixed in a longitudinal position of the wick by means of a snap-in locking connection. The snap-in locking connection provides a secure holding within a given adjustment range. The greatest possible reliability of function is achieved in the sense that on the one hand the degree of evaporation can be adjusted continuously if necessary by simply pressing down the locking connection while on the other hand assurance is provided that the movable heater assembly is held securely in the desired position.
In a preferred embodiment the movable heater assembly is provided with at least one guide arm extending generally perpendicular to the wick axis. The arm is installed with one end of the guide arm in a slot opening in the housing wall for access from the outside of the housing. The guide arm can be made economically without significant expenditure on the movable heater assembly. In addition, the guide arm can serve as an indicator of the currently set distance between the heating element and the wick end by its position in the slot opening, possibly in combination with a scale on the housing area surrounding the slot opening. The guide arm is easily accessible on the other side through such a slot opening for easy maintenance.
At least one guide arm may be used advantageously, held in the slot opening between two end stop positions in the housing wall. To provide an advantageous targeted and controlled guiding of the movable heater assembly, the guiding device may be provided with two guide arms connectable to opposing housing sides. The reliability of function of the movable heater assembly is further enhanced.
The linear guide device preferably has a first guide element on each guide arm approximately parallel to the longitudinal direction of the wick axis. There is a second guide element on the housing corresponding to each first guide element. The first guide element may be in the form of a guide groove and the second guide element in the form of a guide ridge which slides in the guide groove, or vice-versa. To ensure especially simple and reliable positioning, and at the same time simple displacement, the guide ridge may be guided with a friction lock in the guide groove. Advantageously, snap-in openings may be made on the guide ridge, spaced to correspond to different longitudinal distance settings. A snap-in protrusion of the movable heater assembly may be snapped into the opening at a given distance from the wick end to further enhance reliability.
Advantageously, at least one guide arm of the movable heater assembly, approximately perpendicular to the longitudinal direction of the wick axis, carries an electrical heating element. A heating element of this type may be formed by an electric resistance or, in a preferred embodiment, in the form of a ceramic block. Good performance of the entire evaporation device results with the electric heating element in the form of a ceramic block coupled with electric wires. The ceramic block may be mounted on a supporting plate connected to at least one guide arm and can be held in place by means of an elastically attached locking arm. The elastic locking arm may be pre-stressed in the direction of the ceramic block and surrounding the ceramic block laterally in shape of an xe2x80x9cL.xe2x80x9d Complimentary seating ridges formed on the block and supporting plate, preferably made of plastic, make it possible that heat bridges with small surfaces engaging the supporting plate are created. The heat radiation of the ceramic block in the direction of the wick is thus optimized. The locking arms provide secure holding of the ceramic block on the supporting plate in that they can be simply snapped into the latter. Preferably four locking arms are installed on the supporting plate for especially secure holding. In a preferred embodiment, with two guide arms across from each other, the supporting plate is approximately in the center between the two guide arms and in the center of the housing.
A passage for the wick may be made in the ceramic block and correspondingly in the supporting plate. The wick end can be moved through the passage according to the distance that has been selected. The wick passage may, for example, be a circular hole, or a perpendicular recess on the edge. In another advantageous embodiment a distance and/or operational indicator visible through a corresponding opening in the housing be provided on the movable heater assembly. An electric light, e.g. a glow lamp, is preferably provided as the distance and/or operational indicator. In this manner it is can easily be seen from the outside whether the evaporation device is in operation, which is especially advantageous in case an ON/OFF switch is present. At the same time, it can also be used to easily read the position of the movable heater assembly by means of a scale disposed in the area of the housing opening.
Basically, the movable heater assembly can be adjusted continuously or at different incremental positions at different distances from the wick end. In an advantageous embodiment, the movable heater assembly can be displaced between two limit positions constituted by stops formed on the housing side. The movable heater assembly may be located in immediate proximity to the wick end in a first end stop position for a maximum degree of evaporation. The movable heater assembly is preferably located at a distance from the upper wick end as seen from above the wick end in the longitudinal direction of the wick to achieve minimum evaporation. The movable heater assembly may preferably be held in intermediate positions between the two limit positions so that a good individual adjustment of the degree of evaporation to the appliwire requirements is achieved.
The housing itself can be made in different manners depending on the different embodiments. In one advantageous embodiment, the housing has aeration slits and is constructed in a forward housing shell and a rear housing shell removably connected to each other via corresponding locking elements in a locking connection. The rear housing shell may be formed by two housing half-shells which are detachably connected to each other also via corresponding locking elements in a locking connection. In a preferred embodiment, a plane of separation between the half-shells of the rear housing shell is located approximately in a central longitudinal area of the rear housing shell. Preferably the movable heater assembly is mounted on the housing so that it can be displaced longitudinally in the direction of the longitudinal wick axis after assembly or connection of the housing half-shells. The division of the rear housing shells into two housing half-shells makes an easy assembly of the movable heater assembly possible. Thus, for instance, it is possible to thread the guide grooves first on one guide ridge of a first housing half-shell, where two guide arms face each other, and then to install the second housing half-shell on this pre-assembled component. The guide ridge of this second housing half-shell then correspondingly engages the free guide groove of the free guide arm. This results in much greater ease of assembly. The ventilation slits are advantageously made in a housing area near the wick end, so that the evaporated substances can escape upwardly from the housing into the environment.
In principle, connecting the movable heater assembly with electric wires presents no problem in the design according to the invention. The displacement of the movable heater assembly is not so long that an excessive expenditure would be required for long wire lengths to accommodate displacements of the device. However, in order to shield the wires, among other things, from the housing interior in which the container is located, the rear housing shell is made with a double wall when mounted so as to create a wire channel in an advantageous embodiment. The wires can be stowed away in such a wire channel as they go from the heating element to a connection plug so they are shielded from the housing interior. This also ensures that the electrical wires are not in the way when the container is inserted into the housing interior. The rear wall constituting the outer housing wall may be provided with an opening to seat a connection plug so that it an be plugged into a socket. The connection plug in this opening is preferably inserted by means of a complimentary groove and ridge, preferably when the housing half-shells are assembled. In this case, the electric wires go from the connection plug through the wire channel to the heating element. In an especially advantageous embodiment the wires can be fixed in the wire channel in such manner that the wires are somewhat stretched in the second end stop position at maximum distance between the movable heater assembly and the wick end. In this way the longitudinal displacement of the heating element presents no problem with regard to wire lengths due to its longitudinal displacement. Alternately, a passage for the wires may be provided in the rear wall, instead of an opening for a connection plug, so that the housing can also be connected by a wire plugged into a socket far removed from the point of installation.
For simple insertion of the container in the housing with good access, a receiving slot or opening may be provided in the lower housing area through which the container can be introduced and/or screwed into the housing interior where it can be fixed or preferably snapped in detachably. Alternately, it is also possible to provide a passage for the wires in the rear wall instead of an opening for a connection plug so that the housing can be connected by a wire plugged into a socket removed from the point of installation.
For simple insertion of the container in the housing with good access, a receiving slot or opening may be provided in the lower housing area through which the container can be introduced and/or screwed into the housing interior where it can be fixed or preferably snapped in detachably.